1. Field of the Invention
The present invention relates to buses generally and, more specifically, the present invention relates to communications between buses.
2. Background Information
A bus can sometimes be considered to be a collection of wires or other transmission media through which data is transmitted. One part of a computer may communicate with another part of the computer or another piece of equipment outside the computer through a bus. A bus bridge provides a connection path between two independent local buses. One function of a bus bridge is to allow transactions to occur or between a master on one bus and a target on the other.
To illustrate, FIG. 1 shows a bus bridge 113 providing a connection path between bus 109 and bus 111. As shown, bus 109 is part of a host system 101 and bus 111 is part of a peripheral system 103. One example of bus 109 may be the Peripheral Component Integration (PCI) bus. In this example, host system 101 may be a personal computer and peripheral system 103 may be a peripheral coupled to the personal computer. The personal computer would be considered the master and would control peripheral system 103. Host memory 105 of host system 101 is accessible by bus 109 and peripheral memory 107 of peripheral system 103 is accessible by bus 111.
With the configuration illustrated in FIG. 1, host system 101 may communicate with peripheral system 103 through bridge 113. Thus, data may be transmitted back and forth between bus 109 and bus 111 through bridge 113. One characteristic of bridge 113 is that because it assumes that host system 101 is the master, bus exceptions, such as a bus reset 115 for example, are also transmitted through bridge 113. Consequently, if bus 109 is reset through bus reset 115, bus 111 is also reset. Activity on peripheral system 103 is reset and interrupted as a result of bus reset 115 from bus 109.